Cpm 154

rhrocker

rhrocker

Joined
Jan 18, 2004
Messages
1,135
Does CPM 154 have to be cryo'ed? A good source of mine said to do it this way: Ramp to 1400, hold 10 minutes, fast ramp 1950, hold 30 minutes, plate quench & RC is now 61 - 61.5.
Cryo in Ln for 8 hrs, RC is now 62 - 63.5.
Temper twice around 400 - 450 and RC is now 58.5 - 59.

So, what happens if I leave out the cryo? Would the acetone/dry ice method really work very well? I understand it reaches abot -100F or so.
 
The crucible data sheet says it needs to be taken down to 100 dgrees below for complete conversion. If you don't have liquid Nitrogen, then go to your local grocery store and buy a styrofoam cooler big enough to hold your knife and about 5-10 pounds of dry ice and some rubbing alcohol (32 to 64 ounces). Pour the alcohol into the cooler with the dry ice and put your knife in there. It will be about -100 F. Keep it in a well ventilated area so you don't kill yourself and do not put the dry ice in an airtight container because it will blow up from the pressure of the sublimation of CO2. That will work.
-John
 
You friends advice sounds not too far off. Equalizing at 1400 is generally for thicker sections. It probably isn't necessary for blades but sure won't hurt. Crucible says to soak 1 hr at 1950 - and as long as oxygen is excluded, that works very well. Yes, cryo is needed to get the best out of this heat treat. Liquid Nitro lasts longer - Dry ice is easier for most - either will work equally well.

I do disagree about tempering temperature. 400 - 450 is more likely to give you 61-62 RHC. 500 - 600 will give you RHC60 ish - and I doubt you would ever get it down to 58.5 without deteriorating corrosion resitance and toughness.

Rob!
 
I think your friends advice is dead on. He must be a pretty clever guy.
In fact I have used that exact process myself several times. Keeping it at temp for 60 minutes is for +1" thick. I think 30 minutes gets it done. Temper at 450 seems to bring it right in at 59 but occasionally, a stubborn piece might require going up 25F a time until you hit the hardness you want. Do you have a hardness tester?
 
This all is very helpful, thanks guys. Tracy, yes Sir, I have a hardness tester.
 
Yep, That 1 Hr. is per inch of thickness. 15 min works just fine on my deep hollow ground hunters. Ice chest? What keeps the alc. from eating thru it. Accetone works as well. It will eat the chest in no time. Mike
 
On second thought, I think your pal must be a bit of a loony tune. Why is it you are messing around with stainless anyway? You are a pounder. Have you seen the light? Did your friend convert you?
 
tmickley said:
On second thought, I think your pal must be a bit of a loony tune. Why is it you are messing around with stainless anyway? You are a pounder. Have you seen the light? Did your friend convert you?
Click to expand...

Convert? Good gosh NO! My name is Robert Hensarling, I am a alco-pounder. However, this past year I've had some customers asking if I worked with SS, along with the real stuff, carbon steel. Getting commissions/orders nowdays seems to be as tough as it's ever been so, in order to stay competetive, I'm going to learn the ropes required to be proficiant with SS, just for the benefit of my clients. However, when day is done, I'll still be reading my ABS "Anvil" magazines, and watching videos of Bill Moran, Ed Cafferty, Ed Fowler, and many others, effortlessly forge their work, while I dream of firing up my forge and heating up some 52100 first thing in the morning.
 
mlovett said:
Yep, That 1 Hr. is per inch of thickness. 15 min works just fine on my deep hollow ground hunters. Ice chest? What keeps the alc. from eating thru it. Accetone works as well. It will eat the chest in no time. Mike
Click to expand...


Isopropyl alcohol (rubbing alcohol) will not eat through styrofoam. The reason is because it's isopropyl alcohol. Acetone will melt the styrofoam. The alcohol is much less flamable than the acetone.
-John
 
Barker said:
Isopropyl alcohol (rubbing alcohol) will not eat through styrofoam. The reason is because it's isopropyl alcohol. Acetone will melt the styrofoam. The alcohol is much less flamable than the acetone.
-John
Click to expand...

Ok then, so I'll try this rubbing alcohol/dry ice method. I suppose for maximum
cooling, I'd break the DI up into small pecan sized chunks, place it in the styrofoam container, place the knife on top of that, then pour in the alcohol until the knife is covered pretty good, right? Probably be hard to see in there with all of the cloud formations. Ice box Top should then go back on as I wouldn't think that a styrofoam ice box can be sealed up so tight as to cause it to explode apart.
In the meantime, I'll be searching for a DI container dewar and a source for LN, I'm sure there are scads of places in San Antonio.
 
I wouldn't even break up the dry ice. It will be about the size of the container bottom. It will definitely fog up, so fan off the smoke. It will boil too. Then in a few minutes it will make a slush. That's it. You've got the rest. Good luck!
-John
 
I lucked up on some of the first CPM 154CM to come out and have used it almost exclusively since...it seems to grind and polish much better than plain ol 154CM, et. al. ....I love it.

My HT formula:

1900 for 30 minutes, air quench (under a fan on "high" setting) and then temper @ 375 for two hours - three times. As was suggested to me...the third temper makes a bigger difference than I would have imagined with respect to edge holding. Final Rc averages between 60 and 61.

My two cents worth....

Hope everyone has a great weekend.

Hank Hammond
 
Thanks Hank. BTW, do you put your blade in tool wrap? If so, do you leave the wrap on while plate quenching? My loony friend, does. I have to admit, he's actually pretty sharp, except he plays golf instead of learning how to pound on carbon steel.
 
If you are trying to find a used dewar for LN, try stockyards, dairies or breeders. They are mostly used for freezing horse or bull sperm. That's where you will find your best prices. And the semen is in little tubes, not slopping around inside. Just wash it out when you get it.

Gene
 
The semen doesn't give better cryo ??? ...Cryo will give you an extra 1-2 Rc points of hardness. You must use either salt or foil as those high temperatures form scale and decarb very quickly. Plate quench is the most convenient way and do it with the foil on. Please use 30 min as 15 is too short a time for these complex steels !! Dry ice gives -100 F and LN gives -300 F ....Someone here in the past had a problem with warping and after long discussion found he had layed the blade directly on the dry ice therefore producing different conditions on one side from the other ! => warp !
 
With the alcohol / dry ice mix it forms a slush around the knife. I would not just lay the knife on the dry ice. You need to have the alcohol. Also try to position the knives verically like when heat treating them. Please don't think that I think dry ice is better than liquid nitrogen. It's not. I just want to share a less expensive way to cryo until you can get you liquid nitrogen set up.
 
I have been doing recearch for LN2 dewars not only for cheap, but the ones with the smallest boil off measuerment. Some of the bigger ones (50 liters) have a boil off rating of .10-.15 liter, but most of the 10 liter dewars are anywhere from .20-.30 liter. The 50 liter models are overkill for what we use em ofr, unless you cryo 100 blades at a time, not to mention the price tag. The best one I have found so far is maed by International Cryogenics, the 10 liter model has a boil off rate of .21 Liters, and Thomas scientific has em for $460. You might be able to find that exact model used on Ebay for a whole lot cheaper.

http://www.thomassci.com/catalog/product/2212
 
Be careful about focussing to much on boil off rates. a 1" neck will be very efficient but also very hard to stick a bowie knife through.;)

Rob!
 
rhrocker said:
Does CPM 154 have to be cryo'ed? A good source of mine said to do it this way: Ramp to 1400, hold 10 minutes, fast ramp 1950, hold 30 minutes, plate quench & RC is now 61 - 61.5.
Cryo in Ln for 8 hrs, RC is now 62 - 63.5.
Temper twice around 400 - 450 and RC is now 58.5 - 59.

So, what happens if I leave out the cryo? Would the acetone/dry ice method really work very well? I understand it reaches abot -100F or so.
Click to expand...

A 50/50 mixture of dry ice and anti-freeze reaches about -50F to -55F. Acetone might get a little colder, but I doubt it will get to -100F. Dry ice is solid at -112F. With this method however, it is imperitive that you have good quality dry ice. If the dry ice isn't pure and has some water in it, it won't get much lower than about -30F. The water will cause it to freeze up and not be slushy like you want. You can also use industrial alcohol or rubbing alcohol. An alcohol will work as well as acetone, at a much lower cost.

I've helped hundreds of customers freeze bearing races with this method, and I've yet to see one get below -60F. I think the -100F temperatures might not be attainable. Everytime one of my customers tries to go colder it always freezes back up, whether it's good quality dry ice or not.
 
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